Towards Solution-Processed Top-Emitting OLEDs Using a Phosphorescent Iridium Complex

摘要

Phosphorescent inverted top-emitting OLEDs using green iridium complexes have been fabricated by spin coating and their performances compared to bottom-emitting OLEDs based on the same materials. Even if the current efficiency is lower, respectively 7.0 ± 1.1 cd.A^-1 and 12.9 ± 1.9 cd.A^-1, this paper demonstrates the feasibility to fabricate phosphorescent top-emitting OLEDs by using a solution process with a simple OLED structure and replacing indium tin oxide electrode by a low-cost reflective aluminum electrode. Optical characterization of the top-emitting OLEDs shows a low emission shift compared to the spectrum of bottom-emitting OLED. A low angle dependency of the electroluminescence peak wavelength is observed , showing it is possible to control and minimize the microcavity effects for solution-processed top-emitting OLEDs.